[whatwg] Thoughts on video accessibility

Ralph Giles giles at xiph.org
Mon Dec 8 18:46:51 PST 2008

On Mon, Dec 8, 2008 at 6:08 PM, Martin Atkins <mart at degeneration.co.uk> wrote:

> What are the advantages of doing this directly in HTML rather than having
> the "src" attribute point at some sort of compound media document?

The general point here is that subtitle data is in current practice
often created and stored in external files. This is, in part, because
of poor support for embedded tracks in web video applications, but
also arises naturally in production workflow. Moreover, because they
are text, subtitle data is much more likely to be stored in a database
with other text-based content while audio and video is treated as
binary blobs. This scheme is intended to support such hybrid systems.

There is generally a tension between authors wanting to easily
manipulate and add tracks, users wanting a self-contained file, and
search engines wanting stand-alone access to just the text. Because
splitting and merging media files requires special tools, our thinking
in the Ogg accessibility group has been that we need to support both
embedded and external references for text tracks in html. Users (and
their tools) can then choose what methods they want to use in
particular circumstances.

We're also interested in a more sophisticated mechanism for
communicating track assortments between a server and a client, but in
the particular case of text tracks for accessiblity, I think having a
simple, explicit mechanism at the html level is worthwhile.


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